When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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Friday, October 25, 2013

Unprecedented Arctic Warming: Average Summer Temperatures in Last 100 Years May Be Warmest in 120,000 Years

University
of Colorado Boulder Professor Gifford Miller is shown here collecting
dead plant samples from the edge of a Baffin Island ice cap. (Credit:
University of Colorado)

ScienceDaily, October 24, 2013 — The heat is on, at least in
the Arctic. Average summer temperatures in the Eastern Canadian Arctic
during the last 100 years are higher now than during any century in the
past 44,000 years and perhaps as long ago as 120,000 years, says a new
University of Colorado Boulder study.

The study is the first direct evidence the present warmth in the Eastern
Canadian Arctic exceeds the peak warmth there in the Early Holocene,
when the amount of the sun's energy reaching the Northern Hemisphere in
summer was roughly 9 percent greater than today, said CU-Boulder
geological sciences Professor Gifford Miller, study leader. The Holocene
is a geological epoch that began after Earth's last glacial period
ended roughly 11,700 years ago and which continues today.

Miller and his colleagues used dead moss clumps emerging from
receding ice caps on Baffin Island as tiny clocks. At four different ice
caps, radiocarbon dates show the mosses had not been exposed to the
elements since at least 44,000 to 51,000 years ago.

Since radiocarbon dating is only accurate to about 50,000 years and
because Earth's geological record shows it was in a glaciation stage
prior to that time, the indications are that Canadian Arctic
temperatures today have not been matched or exceeded for roughly 120,000
years, Miller said."The key piece here is just how unprecedented the warming of Arctic
Canada is," said Miller, also a fellow at CU-Boulder's Institute of
Arctic and Alpine Research. "This study really says the warming we are
seeing is outside any kind of known natural variability, and it has to
be due to increased greenhouse gases in the atmosphere."A paper on the subject appeared online October 21, 2013 in Geophysical Research Letters,
a journal published by the American Geophysical Union. Co-authors
include CU-Boulder Senior Research Associate Scott Lehman, former
CU-Boulder doctoral student and now Prescott College Professor Kurt
Refsnider, University of California Irvine researcher John Southon and
University of Wisconsin, Madison Research Associate Yafang Zhong. The
National Science Foundation provided the primary funding for the study.

Miller and his colleagues compiled the age distribution of 145
radiocarbon-dated plants in the highlands of Baffin Island that were
exposed by ice recession during the year they were collected by the
researchers. All samples collected were within 1 meter of the ice caps,
which are generally receding by 2 to 3 meters a year. "The oldest
radiocarbon dates were a total shock to me," said Miller.

Located just east of Greenland, the 196,000-square-mile Baffin Island
is the fifth largest island in the world. Most of it lies above the
Arctic Circle. Many of the ice caps on the highlands of Baffin Island
rest on relatively flat terrain, usually frozen to their beds. "Where
the ice is cold and thin, it doesn't flow, so the ancient landscape on
which they formed is preserved pretty much intact," said Miller.

To reconstruct the past climate of Baffin Island beyond the limit of
radiocarbon dating, Miller and his team used data from ice cores
previously retrieved by international teams from the nearby Greenland
Ice Sheet.

The ice cores showed that the youngest time interval from which
summer temperatures in the Arctic were plausibly as warm as today is
about 120,000 years ago, near the end of the last interglacial period.
"We suggest this is the most likely age of these samples," said Miller.The new study also showed summer temperatures cooled in the Canadian
Arctic by about 5 degrees Fahrenheit from roughly 5,000 years ago to
about 100 years ago -- a period that included the Little Ice Age from
1275 to about 1900."Although the Arctic has been warming since about 1900, the most
significant warming in the Baffin Island region didn't really start
until the 1970s," said Miller. "And it is really in the past 20 years
that the warming signal from that region has been just stunning. All of
Baffin Island is melting, and we expect all of the ice caps to
eventually disappear, even if there is no additional warming."Temperatures across the Arctic have been rising substantially in
recent decades as a result of the buildup of greenhouse gases in Earth's
atmosphere. Studies by CU-Boulder researchers in Greenland indicate
temperatures on the ice sheet have climbed 7 degrees Fahrenheit since
1991.A 2012 study by Miller and colleagues using radiocarbon-dated mosses
that emerged from under the Baffin Island ice caps and sediment cores
from Iceland suggested that the trigger for the Little Ice Age was
likely a combination of exploding tropical volcanoes -- which ejected
tiny aerosols that reflected sunlight back into space -- and a decrease
in solar radiation.

1 comment:

What's fascinating with this finding Besides the beauty of imagining island is temperature increase since 70s and the story the little mosses tell on Baffin Island. The way the details of things like C12 to C14 ratio speak.And what's really amazing is how the accounting system of man's financial system doesn't account for Earth heat Runaway rise. And keeper of oil use.. Honor would, even in an Economics exam in college insert disclaimer: 'economics is Off base' -Because Earth is dying now. And Economics needs to be linked forcefully to inference of #s coming from research into what has best chance of keeping Earth from going Hot.-This can be explained using 3rd item insertion to Thermodynamic stability of and health of Open system of Nature Large that holds HZ.. Zeroth Law states price tag on practically well near everything inserted by man's economic hooliganism based #s -that little ditty we inserted has -well it's blatantly clear- Entropy.. Entropy of closed system. Entropy in close system always rises. I propose creating open system or System Economics by use of writ of law 'Act of God' to rewrite contract between mankind and Earth that holds HZ